The chance to watch Meryl Streep or Tommy Lee Jones is often all the encouragement the otherwise reluctant moviegoer needs to risk the kitsch pleasures of “Mamma Mia!”and the familiar genre beats of “Men in Black 3.” The new film “Hope Springs” holds out the delectable promise of watching them work on screen together for the first time, and in a story about a longtime marriage that’s gone dry. It’s a subject that’s as unusual in mainstream American cinema as the sight of major stars letting it all hang out on camera, wrinkles and possibly dignity included, though perhaps not for long, given the movie industry’s growing interest in the country’s aging population.

“Hope Springs” has modest charms to go with its well-matched and practiced pair of wily scene stealers, but the industry will have to do better if it wants to persuade boomers that there’s something for them at the local multiplex other than cartoons and clichés. As directed by David Frankel from a promising screenplay by Vanessa Taylor, the movie is an awkward cross between a domestic comedy and a marital tragedy that’s laced with laughs, soggy with tears and burdened by a booming, blunt soundtrack that amplifies every narrative beat, from “I Don’t Want to Be Your Mother” to “Everybody Plays the Fool,” “Let’s Stay Together” and “It Ain’t Over ’Til It’s Over.”

Mr. Frankel, whose direction in “The Devil Wears Prada” at least had energy, seems uneasy handling the mood swings in “Hope Springs.” When the story takes off, Kay and Arnold (Ms. Streep and Mr. Jones) are celebrating their 31st wedding anniversary at home in Omaha, over dinner with their grown children, a son, Brad (Ben Rappaport), and a daughter, Molly (Marin Ireland). From the outside, both Kay and Arnold’s home life and their jobs seem perfectly normal, if bordering on monotonous. Arnold’s name hangs outside his office at the accounting agency where he works and exchanges bathroom small talk with his colleague and apparently only friend, Vince (Brett Rice); Kay folds tops at the clothing shop where she makes small talk with her colleague and apparently only friend, Eileen (Jean Smart).

Once the children clear out, though, it’s clear that Kay and Arnold are living separate lives. Every night he falls asleep in his lounger while watching a golf show on TV, and they head off to separate bedrooms, and every morning she greets him with bacon, eggs and a smile he doesn’t return. To underline the point, Mr. Frankel stages the breakfast scene enough times that he must have made his way through several dozen fried eggs. It’s obvious, but made lightly funny because of Mr. Jones’s sleepy shuffle and also a bit painful because Ms. Streep lets you see the disappointment in Kay’s face when Arnold makes for the table and his newspaper. Something has to give, and does.

The something turns out to be Dr. Feld (Steve Carell, playing it straight), a therapist Kay discovers through a self-help book and who takes the story into places that Mr. Frankel doesn’t always seem comfortable going. With Dr. Feld’s gentle, insistent encouragement, Kay and Arnold turn the couch into a veritable stage on which they enact a familiar marital drama characterized by swapped accusations, confessed disappointments and exchanged hopes in long scenes that are engaging, if largely on a voyeuristic level, and so cinematically inert that you may find yourself counting the creases on Ms. Streep’s and Mr. Jones’s faces during the many close-ups. The creases are beautiful, and there’s certainly pleasure in watching them undulate across such malleable, movable masks.

Mr. Jones and Ms. Streep keep the therapy scenes lively, despite Mr. Frankel’s stolid direction, as he cuts between Dr. Feld, murmuring thoughtful, Oprah-eseque banalities from his chair, and Kay and Arnold, plopped side by side and sometimes squirming and mugging on the couch. Mr. Frankel has a tougher time once Kay and Arnold, who travel to Maine to work with Dr. Feld, retreat into their separate corners. Mr. Frankel can keep a scene alive when the performers are chattering or on the move, but once silence descends, he seems at a loss. There’s something about the quiet that sends him into a panic, and as he cranks up the tunes and throws in some Maine color, it’s almost as if he realized that his packaged uplift was a bad fit for that elusive American movie screen subject: an honest marriage.